1. Field of the Invention
The present invention relates to a scroll compressor, and more particularly, to an apparatus for varying the capacity of a scroll compressor in which a structure for varying the capacity of a compressor is simplified to reduce the size of the apparatus for varying the capacity of a scroll compressor and to reduce the number of parts.
2. Description of the Background Art
In general, a compressor converts electric energy into kinetic energy that compresses a refrigerant gas. The compressor is a core element that constitutes a freezing cycle system and is divided into various kinds such as a rotary compressor, a scroll compressor, and a reciprocal compressor in accordance with compression mechanism by which refrigerant is compressed. Compressors are used for refrigerators, air conditioners, and show cases.
FIG. 1 is a sectional view illustrating a compressing device of the scroll compressor. FIG. 2 is a plan view illustrating a wrap of a fixed scroll and a wrap of a orbiting scroll that constitutes the compressing device.
As illustrated in the drawings, the compressing device of the scroll compressor includes a fixed scroll 30 mounted in a sealed container 10 so as to be separated from an upper frame 20 mounted in the sealed container 10 by a predetermined distance, a orbiting scroll 40 positioned between the fixed scroll 30 and the upper frame 20 so as to be interlocked with the fixed scroll 30, an Oldham's ring 50 positioned between the orbiting scroll 40 and the upper frame 20 to preventing the rotation of the orbiting scroll 40, a high and low pressure dividing plate 11 combined with the fixed scroll 30 and the sealed container 10 to divide the inside of the sealed container 10 into a high pressure region and a low pressure region, and a discharge valve assembly 60 mounted on the top surface of the fixed scroll 30 to open and close a discharge hole 31 formed in the fixed scroll 30. The orbiting scroll 40 is connected to an eccentric portion 71 of a rotating shaft 70 inserted into the upper frame 20.
A suction pipe 12 into which a gas is inhaled is combined with one side of the sealed container 10 positioned in the low pressure region. A discharge pipe 13 through which a gas is discharged is combined with one side of the sealed container 10 positioned in the high pressure region.
Reference numeral 32 denotes the wrap of the fixed scroll 30 that protrudes in the form of an involute curve. Reference numeral 41 denotes the wrap of the orbiting scroll 40 that protrudes in the form of an involute curve. B denotes bushes. S denotes a sealing member.
The operation of the compressing device of the above-described scroll compressor is as follows.
First, when the rotary force of an electric motor is transmitted to rotate the rotating shaft 70, the orbiting scroll 40 combined with the eccentric portion 71 of the rotating shaft pivots based on the rotating shaft 70. The orbiting scroll 40 pivots in a state where the rotation of the orbiting scroll 40 is prevented by the Oldham's ring 50.
According as the orbiting scroll 40 pivots, the wrap 41 of the orbiting scroll 40 pivots while being engaged with the wrap 32 of the fixed scroll 30 such that a plurality of compression pockets P formed by the wrap 41 of the orbiting scroll 40 and the wrap 32 of the fixed scroll 30 move to the centers of the fixed scroll 30 and the orbiting scroll 40 and that volume changes at the same time. Therefore, a gas is inhaled and compressed and then, is discharged through the discharge hole 31 of the fixed scroll 30.
The high temperature and high pressure gas discharged through the discharge hole 31 of the fixed scroll 30 passes through the high pressure region and is discharged to the outside of the sealed container 10 through the discharge pipe 13.
On the other hand, the above-described scroll compressor commonly constitutes a freezing cycle system to be mainly mounted in air conditioners. In order to minimize power consumption during the operation of an air conditioner, it is necessary to vary the capacity of a scroll compressor that drives the freezing cycle system mounted in the air conditioner.
FIG. 3 is a sectional view illustrating the compressing device of the scroll compressor that includes an example of the conventional apparatus for varying the capacity of a scroll compressor. The same members are denoted by the same reference numerals.
As illustrated in the drawing, the structure of the conventional apparatus for varying the capacity of a scroll compressor is as follows.
A bypass passage K for connecting intermediate pressure compression pockets P under intermediate pressure positioned in the middle of the fixed scroll 30 among the compression pockets P formed by the wrap 32 of the fixed scroll and the wrap 41 of the orbiting scroll to a suction side through which refrigerant is inhaled into the compression pockets P is formed in the fixed scroll 30. The bypass passage K includes a horizontal hole 33 formed so as to be horizontal to the fixed scroll 30, a vertical hole 34 formed so as to be vertical to the fixed scroll 30 and connected to the horizontal hole 33, and a connection hole 35 formed so as to be connected to the top surface of the fixed scroll 30 in the portion where the horizontal hole 33 and the vertical hole 34 are connected to each other. A through hole in which the connection hole 35 and a high pressure chamber are connected to each other is formed in the high and low pressure dividing plate 11.
A first connection pipe 14 for connecting the suction pipe 12 and the discharge pipe 13 to each other is connected between the suction pipe 12 and the discharge pipe 13. A second connection pipe 15 for connecting the first connection pipe 14 and the bypass passage K to each other is connected between the first connection pipe 14 and the bypass passage K. One side of the second connection pipe 15 is combined with the side of the connection hole 35 of the bypass passage K.
A control valve 16 for controlling the direction of the flow of the refrigerant that flows through the first and second connection pipes 14 and 15 is provided in the portion where the first connection pipe 14 and the second connection pipe 15 are connected to each other. A bypass valve 17 for controlling the flow of the refrigerant is provided in the connection hole 35 of the bypass passage K.
The operation of the above-described apparatus for varying the capacity of a scroll compressor will be described as follows.
First, when the scroll compressor is operated at the capacity of 100%, the control valve 16 is positioned such that the second connection pipe 15 and the discharge pipe 13 are connected to each other. When the scroll compressor is operated in the above-described state, since the discharge pipe 13 and the second connection pipe 15 are connected to each other, the bypass valve 17 positioned in the connection hole 35 is pressed by the high pressure refrigerant discharged to the discharge pipe 13 such that the bypass valve 17 is positioned under the connection hole 35 to close the horizontal hole 33 and the vertical hole 34. Therefore, the bypass passage K for connecting the suction side through which the refrigerant is inhaled into the compression pockets P and the compression pockets P under intermediate pressure to each other is closed.
In such a state, the plurality of compression pockets P formed at the edge of the fixed scroll 30 by the wrap 41 of the orbiting scroll and the wrap 32 of the fixed scroll due to the pivoting motion of the orbiting scroll 40 move toward the center of the fixed scroll 30 and, at the same time, volume is reduced such that the refrigerant is compressed. The compression pockets P are continuously formed.
When the scroll compressor is operated at variable capacity, the control valve 16 is moved to connect the second connection pipe 15 and the suction pipe 12 to each other. When the scroll compressor is operated in such a state, since the suction pipe 12 and the second connection pipe 15 are connected to each other, the bypass valve 17 moves to the upper side of the connection hole 35 due to the pressure of the compression pockets P under intermediate pressure applied to the bypass valve 17 such that the bypass passage K is opened. According as the bypass passage K is opened, the pressure of the suction side through which the refrigerant is inhaled into the compression pockets P is equal to the pressure of the compression pockets P in the middle of the fixed scroll 30. Therefore, the compression pockets P positioned in the middle of the fixed scroll 30 move to the center of the fixed scroll 30 and, at the same time volume is reduced such that refrigerant is compressed. Therefore, the pressure of the refrigerant discharged through the discharge hole 31 of the fixed scroll is relatively low.
However, according to the above-described conventional apparatus for varying the capacity of a scroll compressor, since the suction pipe 12 and the discharge pipe 13 are connected to each other by the first connection pipe 14 and the first connection pipe 14 is connected to the second connection pipe 15, the entire structure is complicated and the size of the scroll compressor increases. Therefore, the scroll compressor occupies a large space in an air conditioner and cannot be freely installed in the air conditioner.